Grinding disk fob disk mills



Dec. 29, 1942. K. B EHNSEN L GRINDING DISKSYFOR DISK MILLQS Filed Aug. 12, 1959 1 k X f v firm rag I 6' Karl Be/msen I /8am, #4.

Patented Dec. 29, 1942 GRINDING DISK FOR DESK MILLS Karl Behnsen,

Grossaulieim, near Hanan, Germany; vested in the Alien Property Custodian Application August 12, 1939, Serial No. 289,814

In Germany September 8, 1938 Claims.

It is known per se that grinding disks having triangular, trapezoidal or similarly shaped teeth may be arranged in many different pitches and sizes, and that when grinding material which is sensible to heat, a smearing and undesirable heating of the material owing to the rubbing of the material between the flanks of the teeth may be prevented by choosing teeth which are chamfered or tapered oppositely to the direction of rotation.

Chamfered or tapering teeth of this kind, however, possess the drawback that their tensile strength is greatly reduced owing to the taper, so that even a slight beating of the teeth causes them to snap.

This drawback is eliminated in a simple manner according to the present invention by choosing teeth which, in the individual concentric annular rows, possess the same width and height without tapering in any direction, and by allow- \1 ing the material which is crushed by the cutting edges of the teeth which work in opposite directions to be released immediately at the rear of the cutting edges, for which purpose the individual teeth are inclined against the direction of rotation and arranged upon a foundation surface which is suitably dished or raised in the direction toward the cutting edges of the teeth.

The course of the foundation surface in the individual concentric annular rows of teeth is therefore formed in the shape of waves the widths of which are determined, for example, by the width of the teeth.

Apart from the possibility of being able to prevent an undesired heating of the grist without the necessity of weakening the teeth by reducing their cross-section, a wave-shaped construction of this kind of the foundation carrying the teeth offers the advantage of an increased tensile strength of the grinding disk itself and a positive discharge of the already ground grist in the direction of the periphery of the disk without danger of smearing, as the teeth in the individual concentric annular rows have their front cutting edges on the wave crests whilst the rearwardly directed edges are located in the wave troughs.

'This position of the individual teeth with respect to the plane of grinding may be provided for all the teeth or only for individual groups of teeth, that is to say for example, only in the innermost annular rows of teeth or in the outermost annular rows of teeth, which may for example be designed in the manner of a so-called fine grinding box consisting in practice of a number of concentric annular rows of uniform teeth,

whilst the remaining rows of teeth differ inter se.

The accompanying drawing illustrates by way of example a few constructional forms according to the invention, and in which:

Figure l is a cross section of the two grinding disks engaging with each other along the section line 1-1 of Fig. '7.

Figure 2 is a partial section of the lower grinding disk broken off and represented in perspective according to section line II--II of Fig. 1.

Figure 3 is a partial section of the lower grinding disk according to the section line IlI-III of Fig. 1.

Figure 4 illustrates the cooperation of two grinding teeth fashioned according to the invention, in perspective.

Figures 5 and 6 show top views of runner disks with difierent arrangement of the teeth, the depressions in the grinding disc being indicated by hatching.

Figure '7 shows a partial top View of a disk, two teeth of the upper disk being likewise shown, namely in broken lines.

Taken in detail, a and b designate two grinding disks having the teeth 0 on a and d on b. It will be seen in the drawing that neither the teeth (1 nor the teeth 0 extend parallel to the plane passing through the centre of the base area of the teeth, and through the vertices of the crown of the teeth, but extend in a forwardly inclined direction. In other words the teeth are not located on an even grinding disk but in an inclined direction with respect to a theoretical plane in which corresponding depressions are provided in the disk. This is very clearly shown by Figs. 2 and 3. In this case the individual teeth run from the front cutting edge g in a depression of the bottom of the grinding disk. This depression is to be seen particularly clearly in Fig. 3, in which also the theoretical plane of the grinding disk f is indicated in broken line. Thus each tooth is succeeded by a depression of the grinding disk bottom, which imparts to the latter a wavy shape, at least within a concentric circle. In Fig. 2 said depression is indicated by hatching.

Fig. 4 illustrates very clearly the cooperation of two grinding teeth, a section being shown, in perspective, passing through two grinding disks and only the tooth c of the upper disk being presented for the sake of clarity. The arrow also indicates here, similarly as in Fig. 3, the direction of the movement of the disk b. Appropriate hatching in the bottom of the disk b also indicates the depression entered by the tooth d.

In Figure 5 the teeth h, i and 7c are so arranged that the point of intersection Z and n of their internal edges are always located at the same distance from the centre m of the disk, whilst in Figure 6 the points of intersection and p are located at differing distances from the centre m, that is to say that the teeth are offset within the imaginary appertaining concentric circles q and r. In Figure '7 s designates the tooth for exam ple of the stationary grinding disk, and t designates the tooth of the cooperating rotating disk, the cutting edge u of the tooth if being constantly guided over the flank v of the tooth s.

Owing to the trapezoidal shape of the tooth, the Wedge-shaped slot which is formed between the flanks when a tooth on the rotating disk engages the cooperating tooth on the stationary disk, gradually widens as the front cutting edges of the teeth, after passing gradually travel away from one another in opposite directions, so that the material crushed by the cutting edges is not squashed and rubbed but released as the slot widens or opens.

It has further been found satisfactory to so arrange the teeth that the distances of the points of intersection of the inner lateral edges at the root of the tooth, that is to say the two corners of the root of the tooth which are nearest the centre of the disk, are different, so that the teeth are arranged obliquely within the concentric annular rows which they occupy. When dealing with tough and more especially elastic grist it has finally also been found satisfactory to arrange the grinding teeth according to the invention in such a manner that one edge of the front face of a tooth of one disk passes over the entire flank of the co-operating tooth of the other disk, so that the teeth guide one another mutually. The advantage of this arrangement resides in the fact that the vibrations which occur more especially when dealing with tough and elastic grist, cannot cause a knocking of the teeth which apart from increasing the noise in operation may also lead to the destruction of the teeth. The grinding teeth may vary in shape from row to row or may all be uniform. The size of the teeth may for instance decrease towards the periphery of the disk or may remain the same throughout. In the same way measures may be taken to prevent the tooth tips in the inner annular rows of teeth from coming into contact with the lands,

in subsequent rows the tips may come into contact with the lands and in the outer rows the tips engage the lands more deeply. Furthermore, the teeth may be arranged radially, in curves or in staggered formation.

What I claim and desire to secure by Letters Patent of the United States is:

1. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave on the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk.

2. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the'surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, and the inner line of intersection of the edge at the foot of each tooth with the surface of the disk being disposed at a varying distance from the vertex of the tooth.

3. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned Wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, and at least one of the rows of toothed rings of each of the disks engaging in annular depressions formed between two adjacent concentric rows of teeth on the other disk.

4. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in oircumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, and at least the teeth of one row of the tooth rings of both disks being of less height upon the tooth crests than the smallest distance between the closest portions of the facing surfaces of the two grinding disks.

5. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth ofthe other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, and at least the teeth of one row of the tooth rings on each of the disks engaging in depressions formed between two adjacent concentric rows of teeth on the other disk, and at least the teeth of another row of the tooth rings of both disks being of less height upon the tooth crests than the smallest distance between the closest portions of the facing surfaces of the two grinding disks.

6. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, and the inner line of intersection of the edge with the surface of the disk at the foot of each tooth being disposed at a varying distance from the vertex of the tooth, and at least one of the rows of toothed rings of each of the disks engaging in annular depressions formed between two adjacent concentric rows of teeth on the other disk.

7 In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having th same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of the disk, the inner line of intersection of the edge with the surf-ace of the disk at the foot of each tooth being disposed at a varying distance from the vertex of the tooth, and at least the teeth of one row of the tooth rings of both disks being of less height upon the tooth crests than the smallestdistance between the closest portions of the facing surfaces of the grinding disks.

8. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially extending rows or rings each having the same height and the same width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of th disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at 'least the width of the bottom of the tooth extending circumferentially around the center of the disk, the inner line of intersection of the edge with the surface of the disk at the foot of each tooth being disposed at a varying distance from the vertex of the tooth, at least the teeth of one row of the tooth rings of both disks being of less height upon the tooth crests than the smallest distance between the closest portions of the facing surfaces of the grinding disks, and at least the teeth of one row of the tooth rings on each of the disks engaging in depressions formed between two adjacent concentric rows of teeth on the other disk, and at least the teeth of another row of the tooth rings of both disks being of less height upon the crests of the teeth than the smallest distance between the closest portions of the facing surfaces of the two grinding disks.

9. A mill according to claim 1, in which the teeth in each circumferentially extending ring or row are longitudinally disposed spirally out of parallel with respect to periphery of each grinding disk so that the leading end of each tooth is spaced a shorter distance from the center of its respective grinding disk than the trailing end of the tooth.

10. In a mill having opposite disks movable relatively to each other, with teeth arranged on said disks and the teeth being in circumferentially eX- tending rows or rings each having the same height and the same Width, said teeth being of trapezoidal cross section and upon each disk intermeshing with the teeth of the other disk, the feature of having the teeth at least on one disk and "at least in one tooth ring projecting toward the opposite disk with one front portion of each disposed on the crest of a circumferentially extending wave upon the surface of the grinding side of the disk followed by a trough, with the trailing part of the tooth conforming to the trough of the mentioned wave, the waves and troughs having at least the width of the bottom of the tooth extending circumferentially around the center of of each ring being disthan those of the next the disk, and the teeth posed on diiferent radii adjacent ring.

KARL BEHNSEN. 

